Method of treating iron fluoride



Patented A 1,1939 1' unnel) 's'rA'r'a s PATENT OFFICE v z",1ar,rs4 VSvendSJSvendsen, Madison, Wis assignor, by

meme

Ohio

assignments, to The Sherwin-Williams Commmflieveland, Ohio,

a. 'borporatlo'n oi no Drawing. Application January 13, 19st,

- Serial No.

5 of iron oxide. This application is a continuation in part or mycopending applications Serial, Nos.

614,043 flled May 2'7, 1932 (now Patent No.

2,042,431, granted May 26, 1936) and 745,753 flied September 27, 1934.(now Patent No. 2,042,435,

W granted May 26, 1936). I a

when titanium-bearing ores, especially the ox-.

ide ores such as ilmenite and rutile, are treated, as described in theabove applications, with reactive fluorides, such as ammonium fluorideor am- 5 monium bifluoride, iron fluoride is iormed'with the ironcontained in said ore. The titanium fluoride compound formed may beremoved by leaching the reaction mass resulting from the reactionbetween the ore and the. ammonium fluoride with water or by avolatilization process.

It the reaction mass is not heated high enough to volatilize thetitanium fluoride compound I therefrom and is leached with water todissolve the titanium fluoride compound the residual iron fluoride,being substantially insoluble in water; is

thereby separated from the titanium compound.

The residual iron fluoride is a double fluorideot iron and ammonium.

11' the reaction mass resulting from the heat ing of a mixture ofammonium fluoride and titanium-bearing ore is heated hot enough to re- 4move the titanium fluoride compound as a volatile salt the residual ironfluoride may be the single salt which does not contain ammoniumfluoride-in combination as the double salt.

.It is desirable commercially to recover the fluorine from the ironfluoride formed by the initial reaction. I have found also that iitheiron fluoride is treated in accordance with certain of themethodsdescribed herein an iron 0 oxide is formed which has properties thatmake it desirable as a paint pigment. When iron fluoride andparticularly ferrous fluoride is heated at a, temperature above 300 to400 degrees centigrade in the presence of steam it is reacted upon withthe formation of iron oxide and hydrofluoric acid. This hydrofluoricacid may then be treated with ammonia, which may be taken from thevapors driven oi! during the initial .ore decomposition reaction, toagain iorm ammonium fluoride which may be used to react with furtherquantities oi the titanium-bearing me. It air is not present during thereaction of the steamwith the iron fluoride a black pigment is formed-11 air is present, however, various shades of red iron oxide sired, the

are formed depending upon the temperatures and relative amounts of steamand air which are used v In a specific example the titanium-bearing oresuch as ilmenite is finelyground and is digested with a concentratedsolution of ammonium fluoride or bifluoride in large excess, thedigestion continuing until the temperature reaches 150) to l .80 (3., oruntil most from the reaction mass. The large excess (usually 50% or morethan the stoichiometric amount) of the ammonium fluoride which is of thewater is driven used to secure complete conversion of the ilmenite' intofluorides also has theadvantage of adding the desired-excess of ammoniumfluoride and ammonium bifluoride, or either of them, to the resultingtitanium fluoride, The titanium fluorides so produced apparently aretetrafluorldes. ,The residue, a. grayish paste or powder, is eitherlixiviated with water and filtered, or it is heated to above 300 degreesC. 1f the lixiviation process is used the titanium salts are dissolvedand a double fluoride of iron and ammonia remain,-

these being practically insoluble in water. .If-the reaction mass isheated to above 300 degrees C. the excess ammonium fluoride and titaniumfluoride salts are volatilized from the reaction mass, leaving the'ironfluoride and other non-volatile fluorides, such as-calcium and aluminum,as a.

' residue.

The iron double fluoride residue from the leaching operation is heatedin the presence of steam in a closed furnace to 400-600 C. The vola-vtilized ammonium bifiuoride formed is condensed, and the residual ironoxide which is formed may be used for pigment or abrasive purposes. Thismakes'a black pigment. It a red pigment is dedouble fluoride is firstdecomposed at mil-450 C. whereby the ammonium fluoride is voiatilized,leaving the ferrous fluoride, which is then treated at 500 to 600 C.with moist air.

These two steps may be carried out slmultaneously.

In the method where the titanium fluoride compounds are volatillzed thereaction residue,

which may contain other metallic fluorides such as aluminum and calciumin addition to the iron fluoride, may be heated in an atmosphere ofwater vapor and ammonia, or water vapor alone. Air mayalso be presentwith the water vapor in ordento form the red oxide as previouslydescribed. In both methods the final reaction is between the ironfluoride and the water vapor or the combination of water vapor and air.Iron oxide is formed'in both' cases, and hydrofluoric .acid in the formof a volatile gas is formed unless ammonia also is present. Thehydrofluoric acid may be subsequently combined with ammonia to re-formammoniumfluoride which may be used for treating further quantities ofthe ilmenite ore. The iron fluoride residue from either the leaching orvolatilization process of treating the digested ore also may be'treatedwith ammonium sulfate at a temperature of 300 to 350 C. whereby thereaction results in the formation of ammonium fluoride and iron sulfate.Other fluorides present likewise may be decomposed. The ammoniumfluoride is volatilized from the react ion mass. The iron sulfate may beheated to a red heat whereby iron oxide and sulfur trioxide are formed.The sulfur trioxide may then be reacted with ammonia formed andvolatilized during the initial ore-decomposition reaction to therebyform ammonium sulfate which may be used to decompose further quantitiesof iron fluoride. The reaction therefore is cyclic.

The iron oxide formed by the decomposition oi" the iron fluoride in thepresence of steam alone or-steam and air may contain a small amount ofresidual combined fluorine either due to incomplete reaction or to thepresence of fluorides such as calcium fluoride which are not decomposedby this treatment. Such small amounts of residual fluorides, which haveconsiderable chemical stability, do not seem to afiect the quality ofthe iron oxide when used in paints. 0n the other hand such residualfluorides seem to have some beneficial effect as a preservative againstmold and the like if the paint .produced therefrom is used in moistlocations. The residual combined fluorine usually is present in anamount less than 5 per cent (5%).

In thisapplication I make no distinction between ammonium fluoride andammonium bifluoride in their chemical reaction with the titanium-bearingore. However, physically the two compounds differ, the bifluoridemelting and causing furnace difliculties not encountered with the normalsalt. In the initial reaction ammonia is formed and ammonium fluoride.is consumed. It is understood that reference to these two materials,that is, when they are produced as a result of the reaction they arerecovered and used again in the process.

I claim: 1. In a method of preparing an iron oxide material by treatmentof the residual material comprising iron fluoride which is formed by theseparation of a titanium fluoride compound from a mixture of titaniumfluoride and iron fluoride compounds formed by the heating of atitaniumbearing material containing iron with ammonium fluoride to atemperature high enough to cause a reaction to form said mixture offluoride compounds of titanium and iron, the step which comprisestreating said separated iron-fluoride-containing material with ahydrogen and oxygen containing inorganic compoundwhich forms with saidiron fluoride at temperatures from 300 to 600 C. an oxygen compound ofiron and a volatile fluoride, said treatment being carried out at atemperature high enough to eflect said reaction.

2. In a method of preparing an iron oxide material by treatment of theresidual material comprising iron fluoride which is formed by theseparation of a titanium fluoride compound from a mixture of titaniumfluoride and iron fluoride compounds formed by the heating of atitaniumbearing material containing iron with ammonium fluoride to atemperature high enough to cause a reaction to form said mixture offluoride comthe process is cyclic withpounds of titanium and iron, thestep which comprises heating said separated iron-fluoride-containlngmaterial and treating said heated material with steam while at anelevated temperature, said temperature being sufllciently high to causethe oxygen of said steam to combinewith the iron of said iron fluorideand the hydrogen of said steam to combine with the fluorine of said ironfluoride to form hydrogen fluoride.

3. In a method of preparing an iron oxide material by treatment of theresidual material comprising iron fluoride which is formed by theseparation of a titanium fluoride compound from a mixture of titaniumfluoride and iron fluoride compounds formed by the heating oftitaniumbearing material containing iron with ammonium fluoride to atemperature high enough to cause a reaction to iorm said mixture offluoride compounds of titanium and iron, the step which comprisesheating said separated iron-fluoride-containing material and treatingsaid heated material with steam and air while at an elevated temperature, said temperature being sufficiently high to cause the oxygenof said steam to combine with the iron of said iron fluoride and thehydrogen of said steam to combine said iron fluoride.

4. In a method of preparing an iron oxide material by treatment of theresidual material comprising iron fluoride which is formed by theseparation of a titanium fluoride compound from a mixture of titaniumfluoride and iron fluoride compounds formed by the heating of atitaniumbearing material containing iron with ammonium fluoride to atemperature high enough to cause a reaction to form said mixture offluoride compounds of titanium and iron, the step which comprisesheating said separated iron-fluoride-containing material to 400 to 600C. and treating said heated material with steam while at saidtemperature.

5. In a method of preparing an iron oxide material by treatment of theresidual material comprising iron fluoride which is formed by theseparation of a titanium fluoride compound from a mixture of titaniumfluoride and iron fluoride compounds formed by the heating of atitaniumoxide ore containing iron with ammonium fluoride to atemperature high enough to cause a reaction to form said mixtureoifluoride compounds of titanium and iron, the step which comprisesheating said separated iron-fluoride-containing material and treatingsaid heated material with steam and air while at an elevatedtemperature, said temperature being suflicientiy high and the ratio ofsteam and air being such that the oxygen of said steam combines with theiron of said iron fluoride to form a reddish iron, oxide and thehydrogen of said steam combines with the fluorine of said iron fluorideto form hydrogen fluoride.

6. In a method of preparing an iron oxide material by treatment of theresidual material comprising iron fluoride which is formed by theseparation of a titanium fluoride compound from a mixture of titaniumfluoride and iron fluoride compoundsformed by the heating of atitaniumbearing material containing iron with ammonium fluoride to atemperature high enough to cause a reaction to form-said mixture offluoride compounds of titanium and iron, the steps which compriseheating said residual material at a temperature suflicient to volatilizeammonium fluoride combined with the iron fluoride as a double fluoridesalt of iron and treating said heated remainingmaterial with steam whileat an eleof said iron fluoride and the hydrogen of said vatedtemperature, said temperature being sufflciently high to cause theoxygen of said steam to combine with the iron of said fluoride to formiron oxide and the hydrogen of said steam to combine with the fluorineof said iron fluoride to form hydrogen fluoride. T

'7. In a method of preparing an iron oxide material'by treatment of theresidual material comprising iron fluoride which is termed by theseparation of a titanium fluoride compound formed from a mixture oftitanium fluoride and iron fluoride compounds formed by the heating of atitanimn-bearing material containing iron with ammonium fluoride to atemperature high enough to cause a reaction to form said mixture oi fluoride compounds of titanium and iron, the step which comprises treatingsaid separated ironiEluoride-containing material with steamand air whileat a temperature of t00 to 600 C.

t. In a method of preparing an iron oxide material by the treatmerit'ofiron-containing-mateterials with a reactive fluoride whereby ironfluoride is formed, the steps which comprise heating said iron fluorideand treating said heated material with steam while at an elevatedtemperature, said temperature being sufil-ciently high to cause theoxygen of said steam to combine with the iron steam to combine with thefluorine of said iron fluoride.

9. In a method of preparing an iron oxide material by the treatment ofiron-containing materials with a reactive fluoride whereby iron fluorideis formed, the steps which comprise heating said iron fluoride andtreating said heated fluoride with steam and air while at an elevatedtemperature, said temperature being sufl'iciently high and theproportions of steam and air being such as to cause the oxygen of saidsteam to combine with the iron of said iron fluoride to form a reddishiron oxide and-the hydrogen of said steam to combine with the fluorineof said iron fluoride to form hydrogen fluoride.

10. In a method or preparing an iron oxide material by treatment of theby the action of iron-containing materials with ammonium fluoride, thesteps which comprise heating the iron fluoride formed thereby at atemperature sufficient to volatilize ammonium fluoride associated withsaid iron fluoride and treating said heated residual material with steamwhile at a temperature of 400 to 600 C. l

' SVEND S. SVENDSEN.

iron fluoride formed

